This invention relates to printed circuit boards and particularly to a circuit board for constructing prototypes of systems consisting mainly of an interconnection of integrated circuit (IC) packages.
The primary form of integrated circuit packages in use today includes two parallel rows of conductive pins extending downward from opposite long sides of a rectangularly shaped package, commonly referred to as a dual-in-line package (DIP). The pins are positioned a standard one-tenth inch (0.1 in.) apart along the rows and the two rows of pins are spaced apart an integral multiple of 0.1 inch depending upon the size of the package. The more commonly used integrated circuits have packages with their rows of pins spaced apart 0.2, 0.3, 0.4, 0.6 or 0.9 inch. The length of such packages depends upon the number of pins that are provided and this varies widely. In the course of building and testing a newly designed electronic system, it is desireable to be able to easily assemble and electrically interconnect a large number of such packages of various sizes in a prototype system.
In the development of systems which include integrated circuits, various types of prototyping boards are used. These boards range from perforated breadboards without conductors, to selectively perforated and multilayer plated boards, and to custom laid out boards. In order to accommodate DIP packages, a prototype board contains a pattern of perforations that accept the circuit package pins for mechanical and electrical interconnection. Prototyping circuit boards should satisfy certain requirements, primary among which is versatility. The wider the variety of circuit packages that can be accommodated, the more useful the board is. It is also highly desireable to provide a significant proportion of the circuit board area without perforations and with electrically conductive layers thereon for proper power distribution to the circuit packages. Further, high density positioning of the various size circuit packages is desirable for good electrical performance, as are an efficient pattern of interconnections and high quality conductors. Mechanical characteristics are also important. Unfortunately, these criteria often interfere with each other and must be compromised.
Heretofore, various multilayer prototyping boards have been known in the art, including the Model 347 prototyping board manufactured by MUPAC Corporation of Brockton, Mass. Another manufacturer is the Augat Corporation of Attleboro, Mass. These prototyping boards are generally adapted to wire-wrap type tools and interconnections. Connectors may be provided thereon for power supply and signal inputs and outputs. Substantial areas of the board are generally dedicated to these special functions, which limits layout flexibility. The ability to accommodate various sized DIP's has been achieved in the past through either dedicating areas of the board to different DIP sizes, which imposes adverse constraints on the size and location of different sized DIP's, or by providing a very low density universal pattern.
Because of these constraints, it has not been the practice to lay out a prototype board as it is to be configured in production. Since board production techniques may not have the above described constraints, This drawback has been a particular problem in the design of high speed logic systems, where signal path lengths are crucial and preferably as short as possible. A prototype circuit with incorrect signal path lengths may not be a complete indicator of how the circuit will perform in a production version. Therefore, there is a need for a prototyping board which matches the flexibility and high performance commonly available with production technology.
It is therefore an object of this invention to provide a universal circuit prototyping board that will handle all standard dual-in-line package (DIP) integrated circuit packages.
It is also an object to provide a prototyping board having a generally uniform pattern of socket, component and wiring holes suitable for an efficient pattern of interconnections while optimizing packing density.
It is another object to provide a multilayer prototyping board having holes suitable for any type IC pin socket and for wiring posts, and allowing any type of wiring between sockets, posts, and connectors.
It is yet another object to provide a prototyping board with such flexibility without sacrificing conductive areas on the board that are desirable for efficient power distribution to the integrated circuits mounted on it.
It is an additional object to provide a prototyping board which facilitates the same layout for a prototype circuit as would be used in production.
It is a further object to provide a prototyping board which meets all of the above criteria simultaneously and inexpensively.